Use '.' instead of '' to match any pathspec; needed by git >=2.16

git-fat

@@ -512,6 +512,8 @@ class GitFat(object):
 
     def orphan_files(self, patterns=[]):
         'generator for all orphan placeholders in the working tree'
+        if not patterns or patterns == ['']:
+            patterns = ['.']
         for fname in subprocess.check_output(['git', 'ls-files', '-z'] + patterns).split('\x00')[:-1]:
             digest = self.decode_file(fname)[0]
             if digest: